It’s not uncommon for private health plans to exclude gender transition procedures and medical services related to them. That’s what happened to Gwen Yeh of Seattle, who said her Premera plan wouldn’t pay for hormones or the frequent blood work she needed as part of her move toward living as a woman.

She said she had to find workarounds, such as a doctor who would diagnose her without revealing the connection to her gender transition.

“They have to say that I'm experiencing a hormonal imbalance of some sort, which is true. But if it’s revealed that I'm transitioning, they could deny me the hormones that I need, [which are] offered to other people,” Yeh said.

On Wednesday, Washington Insurance Commissioner Mike Kreidler said companies won’t be allowed to do that anymore. He sent a letter to state insurance companies, laying out his interpretation of state and federal law, which he said guarantees equal treatment for transgender people.

Health plans aren’t required to cover sexual reassignment surgery, but they would have to pay for any related services they cover for other people. Premera, for example, would probably have to cover Yeh’s hormone therapy.

A Premera spokeswoman said the company is still reviewing the letter, and added while some Premera plans do exclude transgender services, others do cover them. Other major carriers either didn’t return calls or declined to comment, as did the professional association for Washington health plans.